1)2(a1+b):4a2=6:5
24a2=10a1+10b
2)40%b=a1=2/5b___________代入1)24a2=4b+10b 24a2=14b a2=7/12b2
3)S长:S正=a1b:a2×a2
=2/5b×b:7/12b×7/12b
=2/5b²:49/144b²
=2/5:49/144
=2/5×144/49
=288/245
=288 :245
1)2(a1+b):4a2=6:5
24a2=10a1+10b
2)40%b=a1=2/5b___________代入1)24a2=4b+10b 24a2=14b a2=7/12b2
3)S长:S正=a1b:a2×a2
=2/5b×b:7/12b×7/12b
=2/5b²:49/144b²
=2/5:49/144
=2/5×144/49
=288/245
=288 :245